libcruft-util/hash/md2.cpp

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/*
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* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
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*
* Copyright 2013 Danny Robson <danny@nerdcruft.net>
*/
#include "md2.hpp"
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#include "../types.hpp"
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#include <array>
#include <algorithm>
#include <cstring>
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///////////////////////////////////////////////////////////////////////////////
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using util::hash::MD2;
using std::array;
using std::begin;
using std::end;
using std::fill;
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///////////////////////////////////////////////////////////////////////////////
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static array<uint8_t,256> S = { {
41, 46, 67, 201, 162, 216, 124, 1, 61, 54, 84, 161, 236, 240, 6, 19,
98, 167, 5, 243, 192, 199, 115, 140, 152, 147, 43, 217, 188, 76, 130, 202,
30, 155, 87, 60, 253, 212, 224, 22, 103, 66, 111, 24, 138, 23, 229, 18,
190, 78, 196, 214, 218, 158, 222, 73, 160, 251, 245, 142, 187, 47, 238, 122,
169, 104, 121, 145, 21, 178, 7, 63, 148, 194, 16, 137, 11, 34, 95, 33,
128, 127, 93, 154, 90, 144, 50, 39, 53, 62, 204, 231, 191, 247, 151, 3,
255, 25, 48, 179, 72, 165, 181, 209, 215, 94, 146, 42, 172, 86, 170, 198,
79, 184, 56, 210, 150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 4, 241,
69, 157, 112, 89, 100, 113, 135, 32, 134, 91, 207, 101, 230, 45, 168, 2,
27, 96, 37, 173, 174, 176, 185, 246, 28, 70, 97, 105, 52, 64, 126, 15,
85, 71, 163, 35, 221, 81, 175, 58, 195, 92, 249, 206, 186, 197, 234, 38,
44, 83, 13, 110, 133, 40, 132, 9, 211, 223, 205, 244, 65, 129, 77, 82,
106, 220, 55, 200, 108, 193, 171, 250, 36, 225, 123, 8, 12, 189, 177, 74,
120, 136, 149, 139, 227, 99, 232, 109, 233, 203, 213, 254, 59, 0, 29, 57,
242, 239, 183, 14, 102, 88, 208, 228, 166, 119, 114, 248, 235, 117, 75, 10,
49, 68, 80, 180, 143, 237, 31, 26, 219, 153, 141, 51, 159, 17, 131, 20,
} };
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///////////////////////////////////////////////////////////////////////////////
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MD2::MD2 ()
{
reset ();
}
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//-----------------------------------------------------------------------------
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void
MD2::reset (void) {
m_total = 0;
fill (begin (C), end (C), 0);
fill (begin (X), end (X), 0);
}
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//-----------------------------------------------------------------------------
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void
MD2::update (const void *data, size_t size)
{ update (static_cast<const uint8_t*> (data), size); }
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//-----------------------------------------------------------------------------
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static const size_t M_OFFSET = 16;
static const size_t M_LENGTH = 16;
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//-----------------------------------------------------------------------------
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void
MD2::update (const uint8_t *data, size_t size) {
uint8_t *M = X + M_OFFSET;
size_t offset = m_total % M_LENGTH;
size_t remain = M_LENGTH - offset;
if (size > remain) {
memcpy (M + offset, data, remain);
transform ();
m_total += remain;
size -= remain;
data += remain;
while (size >= M_LENGTH) {
memcpy (M, data, M_LENGTH);
transform ();
m_total += M_LENGTH;
size -= M_LENGTH;
data += M_LENGTH;
}
offset = 0;
}
memcpy (M + offset, data, size);
m_total += size;
}
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//-----------------------------------------------------------------------------
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MD2::digest_t
MD2::digest (void) const {
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digest_t d;
memcpy (d.data (), X, sizeof (d));
return d;
}
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//-----------------------------------------------------------------------------
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void
MD2::transform (void) {
uint8_t *M = X + M_OFFSET;
// Update the checksum.
// XXX: I can't see why we need the xor-assign from the spec, but it's the
// only change keeping us from conforming to the test-cases. Pulled from a
// review of the reference implementation.
uint8_t L = C[15];
for (size_t i = 0; i < elems (C); ++i)
L = C[i] ^= S[M[i] ^ L];
uint8_t t = 0;
// Setup the blocks
for (size_t i = 0; i < 16; ++i)
X[32 + i] = X[16 + i] ^ X[i];
// Perform the processing rounds
for (size_t i = 0; i < 18; ++i) {
for (size_t j = 0; j < 48; ++j)
t = X[j] = X[j] ^ S[t];
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t = (t + i) % 256;
}
}
void
MD2::finish (void) {
uint8_t *M = X + M_OFFSET;
// Append the padding bytes
size_t offset = m_total % M_LENGTH;
size_t remain = M_LENGTH - offset;
for (size_t i = 0; i < remain; ++i)
M[offset + i] = remain;
transform ();
// Append the checksum
memcpy (M, C, sizeof (C));
transform ();
}